/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * env_getenv.c
 *
 *   Copyright (C) 2007, 2008, 2013 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#ifndef CONFIG_DISABLE_ENVIRON

#include <sched.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>

#include "sched/sched.h"
#include "environ/environ.h"

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: getenv
 *
 * Description:
 *   The getenv() function searches the environment list for a string that
 *   matches the string pointed to by name.
 *
 * Parameters:
 *   name - The name of the variable to find.
 *
 * Return Value:
 *   The value of the valiable (read-only) or NULL on failure
 *
 * Assumptions:
 *   Not called from an interrupt handler
 *
 ****************************************************************************/

FAR char *getenv(const char *name)
{
	FAR struct tcb_s *rtcb;
	FAR struct task_group_s *group;
	FAR char *pvar;
	FAR char *pvalue = NULL;
	int ret = OK;

	/* Verify that a string was passed */

	if (!name) {
		ret = EINVAL;
		goto errout;
	}

	/* Get a reference to the thread-private environ in the TCB. */

	sched_lock();
	rtcb = this_task();
	group = rtcb->group;

	/* Check if the variable exists */

	if (!group || (pvar = env_findvar(group, name)) == NULL) {
		ret = ENOENT;
		goto errout_with_lock;
	}

	/* It does!  Get the value sub-string from the name=value string */

	pvalue = strchr(pvar, '=');
	if (!pvalue) {
		/* The name=value string has no '='  This is a bug! */

		ret = EINVAL;
		goto errout_with_lock;
	}

	/* Adjust the pointer so that it points to the value right after the '=' */

	pvalue++;
	sched_unlock();
	return pvalue;

errout_with_lock:
	sched_unlock();
errout:
	set_errno(ret);
	return NULL;
}

#endif							/* CONFIG_DISABLE_ENVIRON */
